<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
    <title>index page</title>
</head>
<body>
<h1>index page</h1>
<form action="/user/signIn" method="post">
    <input type="text" name="username" value="user-"><br>
    <input type="password" name="password" value="123"><br>
    <input type="submit" value="sign In">
</form>

<a href="/sign_up.jsp">Sign up</a>
<a href="/book.jsp">check</a>
<p style="color: #f00">${requestScope.error}</p>
</body>
</html>